1. Field of the Invention
The present invention relates to an ink-jet ink, an ink cartridge and a recording unit, an ink-jet recording process and an ink-jet recording apparatus using the same, and a method of stabilizing ink ejection properties.
2. Related Background Art
An ink-jet recording method is a recording method in which fine droplets of an ink are ejected to apply the ink to a recording medium such as paper, thereby conducting recording. In particular, according to the ink-jet recording method disclosed in Japanese Patent Publication Nos. 61-59911, 61-59912 and 61-59914, in which an electrothermal converter is used as an ejection-energy-supplying means for an ink, and thermal energy is applied to the ink to generate bubbles, thereby forming droplets of the ink, recording by an On-Demand system and a recording head of a high-density multi-orifice can be realized with ease, and high-resolution and high-quality images can be recorded at a high speed.
However, in such an ink-jet recording method, the interior of a nozzle of a recording head for ejecting the ink communicate with the atmosphere, and so there may occur drying of the ink within the nozzle as well as clogging due to the penetration of foreign matter, bubbles, etc. from the atmosphere in some cases. In order to solve such a problem, there is conducted an ejection operation with no recording, in which an ink is ejected from all nozzles of a recording head toward an ink receiving member (cap), or an ejection-recovery operation, in which the faces of the nozzles of the recording head are capped to apply negative pressure to the nozzle faces by a sucking means such as a pump, thereby forcedly ejecting the ink from the nozzles to solve the clogging of the nozzles. At this time, in the case of, particularly, a long recording head in which a number of nozzles are arranged, or the like, a large amount of the ink is ejected by the above-described ejection operation with no recording or ejection-recovery operation irrespective of a recording operation. Therefore, such an operation involves a problem that the amount of the ink consumed is increased to raise the running cost of the apparatus. Thus, an ink-jet recording apparatus equipped with a structure in which a large amount of the ink ejected by the ejection with no recording or the ejection-recovery operation can be recycled has also been developed.
However, a large amount of the ink ejected at the time when a physical operation for preventing the clogging of nozzles, such as the above-described ejection with no recording or ejection-recovery operation, is conducted may undergo changes in its ink composition and ink properties in some cases due to evaporation of water and the like by exposure to the atmosphere. When such a recycled ink is used for recording, therefore, image quality may be impaired in some cases.
In an ink-jet recording apparatus of the On-Demand system in particular, an ink is not always ejected from all nozzles, but only an ink required for the formation of an image is ejected from some nozzles in case of necessity. Therefore, a state that no ink flows in a nozzle often occurs. When the state that no ink flows in a nozzle continues over a long period of time, specifically, for example, when there occurs such a situation that the time period during which an ink within a nozzle confronts a recording medium without being subjected to no ejection-recovery operation exceeds 5 seconds, a coloring material may crust at, particularly, an orifice part of the recording head in some cases due to evaporation of water and the like from the orifice, resulting in clogging at the orifice to fail to smoothly conduct recording. As a countermeasure against such a phenomenon, the ejection with no recording or ejection-recovery operation is conducted as described above. When the ink used in the ejection with no recording or ejection-recovery operation is recycled, however, the recycled ink may undergo changes of its ink composition and ink properties in some cases due to evaporation of water and the like by exposure to the atmosphere as described above. Therefore, this phenomenon may become particularly remarkable in some cases. Further, when the evaporation of water and the like from the orifice occurs, the ink tends to cause viscosity increase at the orifice part of the head, and its start-up properties may be deteriorated in some cases.
Further, the present inventors have had a finding that there is a possibility that the deterioration of such start-up properties as described above and the like may become a more serious problem in an ink-jet printer in which images and the like are recorded while a recording head is fixed. More specifically, in the case of an ink-jet printer which makes a record of images and the like by scanning a recording head, the state that no ink flows in a nozzle can be prevented from continuing over a long period of time, since an ejection-recovery operation can be frequently conducted in the course of a recording operation. In the ink-jet printer in which the recording head is fixed during a recording operation, however, it is difficult to conduct the ejection-recovery operation of the recording head in the course of the recording operation, and so such a situation that the state that no ink flows in a nozzle continues over a long period of time tends to occur. The present inventors have been led to the recognition that when an ink used for the ejection-recovery operation in such a printer is intended to be recycled, a countermeasure against a change in ink composition of the recycled ink and a resultant change in ink-jet ejection properties is a more important technical problem.
It is accordingly an object of the present invention to provide an ink-jet ink which is hard to undergo a change in ink composition even when it is recycled after used in the above-described ejection with no recording or ejection-recovery operation, since the ink is hard to undergo evaporation of water and a solvent, or hard to undergo a change in ink ejection properties even when the ink composition is changed, so as to stably exhibit good ejection properties.
Another object of the present invention is to provide an ink-jet recording process by which a high-quality recorded article can be obtained at a reasonable cost.
A further object of the present invention is to provide an ink-jet recording apparatus by which a high-quality recorded article can be stably obtained at a reasonable cost, and an ink cartridge and a recording unit which can be used in such a recording apparatus.
A still further object of the present invention is to provide a method of stabilizing ink ejection properties in an ink-jet printer equipped with a mechanism with which an ink is recycled.
The above objects can be achieved by the present invention described below.
According to an embodiment of the present invention, there is thus provided an ink-jet ink comprising (A) diethylene glycol, (B) at least one of trimethylolpropane and ethyleneurea, (C) a glycol having a vapor pressure lower than that of diethylene glycol at 20xc2x0 C., (D) a coloring material, and (E) water, wherein the total amount of the components (A), (B) and (C) is 10 to 40% by weight based on the total weight of the ink.
According to an embodiment of the present invention, there is also provided an ink cartridge comprising an ink container portion containing the ink described above.
According to an embodiment of the present invention, there is further provided a recording unit comprising an ink container portion containing the ink described above, and a head portion for ejecting the ink therefrom.
According to an embodiment of the present invention, there is still further provided an ink-jet recording process, comprising the step of ejecting an ink from an orifice toward a recording surface with an On-Demand system by applying energy to an ink comprising (A) diethylene glycol, (B) at least one of trimethylolpropane and ethyleneurea, (C) a glycol having a vapor pressure lower than that of diethylene glycol at 20xc2x0 C., (D) a coloring material, and (E) water, wherein the total amount of the components (A), (B) and (C) is 10 to 40% by weight based on the total weight of the ink.
According to an embodiment of the present invention, there is yet still further provided an ink-jet recording apparatus, comprising a recording head for ejecting the ink described above therefrom, and an ink cartridge having an ink container portion containing the ink.
According to another embodiment of the present invention, there is yet still further provided an ink-jet recording apparatus, comprising a recording unit having an ink container portion containing the ink described above and a head for ejecting the ink therefrom.
According to a further embodiment of the present invention, there is yet still further provided an ink-jet recording apparatus, comprising an ink container portion containing an ink comprising (A) diethylene glycol, (B) at least one of trimethylolpropane and ethyleneurea, (C) a glycol having a vapor pressure lower than that of diethylene glycol at 20xc2x0 C., (D) a coloring material, and (E) water, wherein the total amount of the components (A), (B) and (C) is 10 to 40% by weight based on the total weight of the ink, a recording head for ejecting the ink therefrom, and a means for collecting the ink ejected from the recording head in the ink container portion.
According to a still further embodiment of the present invention, there is yet still further provided an ink-jet recording apparatus, comprising an ink container portion containing an ink comprising (A) diethylene glycol, (B) at least one of trimethylolpropane and ethyleneurea, (C) a glycol having a vapor pressure lower than that of diethylene glycol at 20xc2x0 C., (D) a coloring material, and (E) water, wherein the total amount of the components (A), (B) and (C) is 10 to 40% by weight based on the total weight of the ink, a recording head for ejecting the ink therefrom, an ink-receiving member for receiving the ink ejected from the recording head, an ink flow path connecting the ink-receiving member to the ink container portion, and a pump for collecting the ink received with the ink-receiving member in the ink container portion.
According to another embodiment of the present invention, there is yet still further provided an ink-jet recording process using the ink-jet recording apparatus described above, which comprises the step of ejecting an ink containing the ink-jet ink previously ejected at least once from the recording head.
According to a further embodiment of the present invention, there is yet still further provided an ink-jet recording process, comprising the step of ejecting an ink containing an ink-jet ink previously ejected at least once from a recording head, wherein the ink-jet ink is an ink-jet ink comprising (A) diethylene glycol, (B) at least one of trimethylolpropane and ethyleneurea, (C) a glycol having a vapor pressure lower than that of diethylene glycol at 20xc2x0 C., (D) a coloring material, and (E) water, wherein the total amount of the components (A), (B) and (C) is 10 to 40% by weight based on the total weight of the ink.
According to a further embodiment of the present invention, there is yet still further provided a method of stabilizing ink ejection properties in an ink-jet recording process comprising the step of ejecting an ink containing an ink-jet ink previously ejected at least once from a recording head, wherein the ink-jet ink comprises (A) diethylene glycol, (B) at least one of trimethylolpropane and ethyleneurea, (C) a glycol having a vapor pressure lower than that of diethylene glycol at 20xc2x0 C., (D) a coloring material, and (E) water, wherein the total amount of the components (A), (B) and (C) is 10 to 40% by weight based on the total weight of the ink.